Spectrum - Browser-based app to visualize the frequencies of an audio file.
Q-Stats - Get free marketing insights for every question on Quora.
Roomvine - Chatrooms for real life venues, neighborhoods and events
Site Rank Data - View historical rank information of websites via time series charts.
Treadie - Create your own micro-social network for topics
HypeStat - HypeStat is free statistics and analytics service, where you can find information about every website.